Network Working Group
Request for Comments: 4498
Category: Experimental
G. Keeni
Cyber Solutions Inc.
May 2006

The Managed Object Aggregation MIB

Status of This Memo

This memo defines an Experimental Protocol for the Internet community. It does not specify an Internet standard of any kind. Discussion and suggestions for improvement are requested. Distribution of this memo is unlimited.

Copyright Notice

Copyright © The Internet Society (2006).

IESG Note

The content of this RFC was at one time considered by the IETF, and therefore it may resemble a current IETF work in progress or a published IETF work. This RFC is not a candidate for any level of Internet Standard. The IETF disclaims any knowledge of the fitness of this RFC for any purpose and in particular notes that the decision to publish is not based on IETF review for such things as security, congestion control, or inappropriate interaction with deployed protocols. The RFC Editor has chosen to publish this document at its discretion. Readers of this RFC should exercise caution in evaluating its value for implementation and deployment. See RFC 3932 for more information.

Abstract

This memo defines a portion of the Management Information Base (MIB), the Aggregation MIB modules, for use with network management protocols in the Internet community. In particular, the Aggregation MIB modules will be used to configure a network management agent to aggregate the values of a user-specified set of Managed Object instances and to service queries related to the aggregated Managed Object instances.

Table of Contents

   1. The Internet-Standard Management Framework ......................2
   2. Background ......................................................2
   3. MO Aggregation: The Concept .....................................3
   4. The Requirements for Managed Object Aggregation .................6
   5. MIB Design ......................................................6
   6. The Aggregation MIB Modules .....................................7
   7. Security Considerations ........................................25
   8. IANA Considerations ............................................27
   9. References .....................................................27
      9.1. Normative References ......................................27
      9.2. Informative References ....................................27
   10. Acknowledgements ..............................................28

1. The Internet-Standard Management Framework

For a detailed overview of the documents that describe the current Internet-Standard Management Framework, please refer to section 7 of RFC 3410 [RFC3410].

Managed objects are accessed via a virtual information store, termed the Management Information Base or MIB. MIB objects are generally accessed through the Simple Network Management Protocol (SNMP).

Objects in the MIB are defined using the mechanisms defined in the Structure of Management Information (SMI). This memo specifies a MIB module that is compliant to the SMIv2, which is described in STD 58, RFC 2578 [RFC2578], STD 58, RFC 2579 [RFC2579] and STD 58, RFC 2580 [RFC2580].

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14, RFC 2119 [RFC2119].

2. Background

For the purpose of management, it is necessary to access Managed Objects (MOs). The SNMP framework provides a mechanism for naming and describing managed objects. These objects are accessed via a virtual information store termed a Management Information Base (MIB). MIBs have been defined by equipment, protocol, and application developers to provide management access to the managed entities. We will call the MOs defined in these MIBs simple MOs (SMO). Management applications will access one or more instances of these SMOs, one or more times, to monitor the target entity.

There is a cost associated with accessing MOs. The cost is the network bandwidth and the packet header processing overhead at the command generator (manager) and the command responder (agent). This cost constrains the number of MO instances that can be polled and the interval at which polling can be carried out.

The overhead reduction can be carried out by reducing the number of query-response packets. This will reduce the packet processing overhead, and to some extent, the bandwidth.

The payloads in a typical SNMP "get" packet and the corresponding response are as shown in Figure 1. In this example, polling is carried out for 'n' Managed Object instances OID1, OID2, ..., OIDn. It is obvious that a substantial amount of the payload in an SNMP packet consists of the OIDs.

3. MO Aggregation: The Concept

In this document, a mechanism of MO aggregation for payload compression is defined. The idea is simple: we introduce the concept of an Aggregate MO (AgMO). An AgMO is just another MO as far as the SNMP protocol is concerned. No new protocol operations will be required to handle these MOs. As in the case of any other MO, it requires additional instrumentation at the command responder (agent) and at the (command generator) manager. In this mechanism, the user defines an Aggregate MO (AgMO) corresponding to one or more (predefined) MO instances. Semantically, the value of an AgMO instance will be equivalent to the concatenation of the values of the corresponding MO instances. The order of the concatenation will be determined by the order in which the MO instances are specified in the AgMO definition. With the definitions done, the user can, as and when the necessity arises, do an SNMP 'get' on instances of the AgMO to fetch the value of the constituent MO instances. There is substantial savings on bandwidth, as only one instance object identifier is carried in the request and the response. In the normal case, instance object identifiers for each of the constituent MO instances would be carried in the requests and the responses. This is the basic concept of Aggregate Managed Objects. For every AgMO, an ErrorStatus Managed Object is defined. This MO indicates errors, if any, that have been encountered while fetching the values of the constituent MO instances. The error indication is comprised of the index of the MO instance and the corresponding error. If there are no errors, the ErrorStatus Managed Object instance will have a null value. This is the basic concept of Aggregate Managed Objects.

The concepts are explained in Figure 2. An aggregate managed object, AgMOx, has been defined for the MO instances MOI1, ... MOIn. The value of an instance of AgMOx will be a concatenation of the values of MOI1, ... MOIn, in that order.

Polling for MO Instances [MOI1, MOI2, ... MOIn]:

                +--------+------+-------+... -+------+------+
         Query: |Get req | MOI1 | NULL  |     | MOIn | NULL |
                +--------+------+-------+... -+------+------+
      
                +--------+------+-------+... -+------+------+
      Response: |Get resp| MOI1 | Val1  |     | MOIn | Valn |
                +--------+------+-------+... -+------+------+

Figure 1. Polling for MO instances

Polling for an instance (AgMOIx) of an aggregate MO (AgMOx):

      AgMOx = aggr{AgMOI1, AgMOI2, ......AgMOIn}
      
                +--------+--------+-------+
         Query: |Get req | AgMOIx | NULL  |
                +--------+--------+-------+
      
                +--------+--------+------------------------+
      Response: |Get resp| AgMOIx |    Val1,Val2,...,Valn  |
                +--------+--------+------------------------+

Figure 2. MO aggregation

As a further refinement of the AgMO, we introduce the Time-Based Aggregated Managed Object (TAgMO). The TAgMO is an MO that represents the values of a user-specified MO instance sampled at user-specified intervals for a user-specified number of times. In this case, the user defines a TAgMO by specifying the MO instance that needs to be sampled, the sampling interval, and the desired number of samples that will be included in one TAgMO. The value of a TAgMO instance will include the timestamp (sysUpTime) at which the first sample was taken. The start time is not specified when the TAgMO is defined. Implementations may choose to align the start time with the appropriate time boundaries (e.g., seconds, minutes, hours). With the definitions, the user can do an SNMP "get" on an instance of the TAgMO to fetch the values of the constituent MO instance sampled at the specified intervals. This is the concept of Time-Based aggregation.

Polling for 'n' samples of an MO Instance [MOI] at an interval 'i':

                Query               Time         Response
                =====               ====         ========
      +--------+-----+-----------+
      |Get req | MOI |    NULL   |  t
      +--------+-----+-----------+  :    +--------+-----+--------------+
                                    :    |Get resp| MOI |    Val(t)    |
                                    :    +--------+-----+--------------+
      +--------+-----+-----------+  t+i
      |Get req | MOI |    NULL   |  :
      +--------+-----+-----------+  :    +--------+-----+--------------+
                                    :    |Get resp| MOI |    Val(t+i)  |
                                    X    +--------+-----+--------------+
                                    X
                                    :
      +--------+-----+-----------+  t+(n-1)i
      |Get req | MOI |    NULL   |  :
      +--------+-----+-----------+  :    +--------+-----+--------------+
                                    :    |Get resp| MOI | Val(t+(n-1)i)|
                                         +--------+-----+--------------+

Figure 3. Periodic polling for samples of an MO instance

Polling for an instance (TAgMOIx) of a Time-Based aggregate MO (TAgMOx):

TAgMOx = aggr{'n' polled samples of an instance (MOI) of MO

at intervals = 'i' microseconds}

             +--------+---------+-------+
      Query: |Get req | TAgMOIx | NULL  |
             +--------+---------+-------+
   
             +--------+---------+--------------------------------------+
   Response: |Get resp| TAgMOIx | t,Val(t),Val(t+i),.,Val(t + (n-1)*i) |
             +--------+---------+--------------------------------------+

Figure 4. Time-Based aggregation

The TAgMO instance is a "bucket" of data representing the value of the corresponding MO instance sampled at 'i' microsecond intervals, 'n' times (i.e., over a 'n' X 'i' microsecond window). The TAgMO instance value gets updated at 'n' X 'i' microsecond intervals.

4. The Requirements for Managed Object Aggregation

The general requirements of managed object aggregation are as follows:

o It should lead to fewer packets.
o It should lead to less bandwidth consumption.
o It should not lead to loss of information.

In the case of Time-Based aggregation, there will be a delay involved in getting the actual data. The minimum delay in this case will be the duration of the aggregation.

The manager application is expected to configure AgMOs (Aggregate MOs) and TAgMOs (Time-Based Aggregate MOs) with care so that the response size is not too large. In case the resultant response size is larger than the maximum acceptable message size of the originator or larger than the local maximum message size, then the error-status field will be set to "tooBig".

Note that an aggregate MO can be defined only when all the constituent MO instances of interest are known. This scheme cannot be employed if a manager/application does not know the specific MO instances (of interest) that are serviced by the management target. In such cases, the application may "discover" the MO instances of interest by some means, e.g., by "walking" through the MIB tree on the agent. According to the results of the "walk", the application can define an appropriate aggregate MO that will serve the purpose. Considering the cost involved in this exercise, this method is recommended only if the aggregate MO will be used repeatedly, so that the benefits of aggregation outweigh the costs of configuration.

5. MIB Design

The basic principle has been to keep the MIB as simple as possible and at the same time to make it flexible enough that a large number of users and applications can use the MIB to configure aggregate MOs conveniently.

Two separate MIB modules have been defined. The AggrMIB supports the aggregation of independent MO instances, while TAggrMIB supports the aggregation of several samples of the same MO instance. Both of these MIB modules use the textual conventions defined in RMON-MIB [RFC2819] and SNMP-FRAMEWORK-MIB [RFC3411].

The AggrMIB is comprised of three tables, described below.

  • The aggrCtlTable controls the aggregation process. Each row in this table defines the attributes of the aggregate object defined in the aggrMOTable.
   -  The aggrMOTable defines the primary MO-based aggregation, i.e.,
      the MOs that will be aggregated.
  • The aggrDataTable contains the details of the aggregated object.

The TAggrMIB is comprised of two tables described below.

  • The tAggrCtlTable controls the aggregation process. Each row in this table defines the attributes of the aggregate object defined in the aggrMOTable.
  • The tAggrDataTable contains the details of the aggregated object.

6. The Aggregation MIB Modules

AGGREGATE-MIB DEFINITIONS ::= BEGIN

IMPORTS

         MODULE-IDENTITY,  experimental, Unsigned32,
         OBJECT-TYPE, Opaque
                    FROM SNMPv2-SMI
         OwnerString
                    FROM RMON-MIB
         RowStatus, StorageType, TEXTUAL-CONVENTION
                    FROM SNMPv2-TC
         MODULE-COMPLIANCE, OBJECT-GROUP
                    FROM SNMPv2-CONF
         SnmpAdminString
                    FROM SNMP-FRAMEWORK-MIB;

aggrMIB MODULE-IDENTITY

          LAST-UPDATED "200604270000Z"        --  27th April, 2006
          ORGANIZATION "Cyber Solutions Inc. NetMan Working Group"
          CONTACT-INFO
         "                      Glenn Mansfield Keeni
                        Postal: Cyber Solutions Inc.
                                6-6-3, Minami Yoshinari
                                Aoba-ku, Sendai, Japan 989-3204.
                           Tel: +81-22-303-4012
                           Fax: +81-22-303-4015
                        E-mail: glenn@cysols.com

Support Group E-mail: mibsupport@cysols.com"

DESCRIPTION

"The MIB for servicing aggregate objects.

                      Copyright © The Internet Society (2006).  This
                      version of this MIB module is part of RFC 4498;
                      see the RFC itself for full legal notices.
                     "
             REVISION    "200604270000Z"      -- 27th April, 2006
             DESCRIPTION "Initial version, published as RFC 4498."
                  ::= { experimental 123 }

AggrMOErrorStatus ::= TEXTUAL-CONVENTION

        STATUS       current
        DESCRIPTION
          "This data type is used to model the error status of the
           constituent MO instances.  The error status for a
           constituent MO instance is given in terms of two elements:
             o The moIndex, which indicates the position of the MO
               instance (starting at 1) in the value of the aggregated
               MO instance.
             o The moError, which indicates the error that was
               encountered in fetching that MO instance.
           The syntax in ASN.1 Notation will be
           ErrorStatus :: = SEQUENCE {
              moIndex  Integer32,
              moError  SnmpPduErrorStatus
           }
           AggrMOErrorStatus ::= SEQUENCE OF {
              ErrorStatus
           }
           Note1: The command responder will supply values for all
                  constituent MO instances, in the same order in
                  which the MO instances are specified for the AgMO.
                  If an error is encountered for an MO instance, then
                  the corresponding value will have an ASN.1 value NULL,
                  and an error will be flagged in the corresponding
                  AggrMOErrorStatus object.
                  Only MOs for which errors have been encountered will
                  have their corresponding moIndex and moError values
                  set.
           Note2: The error code for the component MO instances will be
                  in accordance with the SnmpPduErrorStatus TC defined
                  in the DISMAN-SCHEDULE-MIB [RFC3231].
           Note3: The command generator will need to know
                  constituent MO instances and their order to correctly
                  interpret AggrMOErrorStatus.
          "
        SYNTAX      Opaque (SIZE (0..1024))

AggrMOValue ::= TEXTUAL-CONVENTION

        STATUS       current
        DESCRIPTION
          "This data type is used to model the aggregate
           MOs.  It will have a format dependent on the constituent
           MOs, a sequence of values.  The syntax in ASN.1 Notation will
           be
           MOValue :: = SEQUENCE {
                value ObjectSyntax
           }
           where 'value' is the value of a constituent MO instance.
           AggrMOValue :: = SEQUENCE OF {
               MOValue
           }
        
           Note: The command generator will need to know the
           constituent MO instances and their order to
           correctly interpret AggrMOValue."
        SYNTAX      Opaque (SIZE (0..1024))

AggrMOCompressedValue ::= TEXTUAL-CONVENTION

        STATUS       current
        DESCRIPTION
          "This data type is used to model the compressed
           aggregate MOs."
        SYNTAX      OCTET STRING (SIZE (0..1024))
   
   --
   -- The aggregation control table
   -- There will be a row for each aggregate MO
   --
      aggrCtlTable OBJECT-TYPE
           SYNTAX  SEQUENCE OF AggrCtlEntry
           MAX-ACCESS  not-accessible
           STATUS current
           DESCRIPTION
             "A table that controls the aggregation of the MOs."
           ::= {aggrMIB 1}

aggrCtlEntry OBJECT-TYPE

           SYNTAX  AggrCtlEntry
           MAX-ACCESS  not-accessible
           STATUS  current
           DESCRIPTION
             "A row of the control table that defines one aggregated
              MO.
           
              Entries in this table are required to survive a reboot
              of the managed entity depending on the value of the
              corresponding aggrCtlEntryStorageType instance.
             "
           INDEX {aggrCtlEntryID }
           ::= {aggrCtlTable 1 }
       
       AggrCtlEntry ::= SEQUENCE {
          aggrCtlEntryID
                        SnmpAdminString,
          aggrCtlMOIndex
                        Unsigned32,
          aggrCtlMODescr
                        SnmpAdminString,
          aggrCtlCompressionAlgorithm
                        INTEGER,
          aggrCtlEntryOwner
                        OwnerString,
          aggrCtlEntryStorageType
                        StorageType,
          aggrCtlEntryStatus
                        RowStatus
       }

aggrCtlEntryID OBJECT-TYPE

           SYNTAX SnmpAdminString (SIZE(1..32))
           MAX-ACCESS not-accessible
           STATUS current
           DESCRIPTION
             "A locally unique, administratively assigned name
              for this aggregated MO.  It is used as an index to
              uniquely identify this row in the table."
           ::= { aggrCtlEntry 1 }

aggrCtlMOIndex OBJECT-TYPE

           SYNTAX Unsigned32 (1..2147483647)
           MAX-ACCESS read-create
           STATUS current
           DESCRIPTION
             "A pointer to a group of MOs identified by aggrMOEntryID
              in the aggrMOTable.  This is the group of MOs that will
              be aggregated."
           ::= { aggrCtlEntry 2 }

aggrCtlMODescr OBJECT-TYPE

           SYNTAX SnmpAdminString (SIZE(0..64))
           MAX-ACCESS read-create
           STATUS current
           DESCRIPTION
             "A textual description of the object that is
              being aggregated."
           ::= {aggrCtlEntry 3}

-- only one compression algorithm is defined as of now. aggrCtlCompressionAlgorithm OBJECT-TYPE

           SYNTAX INTEGER {
                  none      (1),
                  deflate   (2)
           }
           MAX-ACCESS read-create
           STATUS current
           DESCRIPTION
             "The compression algorithm that will be used by
              the agent to compress the value of the aggregated
              object.
              The deflate algorithm and corresponding data format
              specification is described in RFC 1951.  It is
              compatible with the widely used gzip utility.
             "
           REFERENCE
             "RFC1951 : DEFLATE Compressed Data Format Specification
              version 1.3
             "
           DEFVAL { none }
           ::= {aggrCtlEntry 4}

aggrCtlEntryOwner OBJECT-TYPE

           SYNTAX OwnerString
           MAX-ACCESS read-create
           STATUS current
           DESCRIPTION
             "The entity that created this entry."
           ::= {aggrCtlEntry 5}

aggrCtlEntryStorageType OBJECT-TYPE

SYNTAX StorageType
MAX-ACCESS read-create
STATUS current
DESCRIPTION

"This object defines whether the parameters defined in

this row are kept in volatile storage and lost upon reboot or backed up by non-volatile (permanent) storage.

Conceptual rows having the value 'permanent' need not allow write-access to any columnar objects in the row.

              "
           ::= {aggrCtlEntry 6}

aggrCtlEntryStatus OBJECT-TYPE

           SYNTAX RowStatus
           MAX-ACCESS read-create
           STATUS current
           DESCRIPTION
              "The row status variable, used according to row
               installation and removal conventions.
               Objects in a row can be modified only when the value of
               this object in the corresponding conceptual row is not
               'active'.
               Thus, to modify one or more of the objects in this
               conceptual row,
                 a. change the row status to 'notInService',
                 b. change the values of the row, and
                 c. change the row status to 'active'.
               The aggrCtlEntryStatus may be changed to 'active' if
               all the MOs in the conceptual row have been assigned
               valid values.
              "
           ::= {aggrCtlEntry 7}
   
   --
   -- The Table of primary(simple) MOs
   --
      aggrMOTable OBJECT-TYPE
           SYNTAX  SEQUENCE OF AggrMOEntry
           MAX-ACCESS  not-accessible
           STATUS current
           DESCRIPTION
              "The table of primary(simple) MOs that will be aggregated.
               Each row in this table represents a MO that will be
               aggregated.  The aggrMOEntryID index is used to identify
               the group of MOs that will be aggregated.  The
               aggrMOIndex instance in the corresponding row of the
               aggrCtlTable will have a value equal to the value of
               aggrMOEntryID.  The aggrMOEntryMOID index is used to
               identify an MO in the group.
              "
           ::= {aggrMIB 2}

aggrMOEntry OBJECT-TYPE

           SYNTAX  AggrMOEntry
           MAX-ACCESS  not-accessible
           STATUS  current
           DESCRIPTION
              "A row of the table that specifies one MO.
               Entries in this table are required to survive a reboot
               of the managed entity depending on the value of the
               corresponding aggrMOEntryStorageType instance.
              "
           INDEX { aggrMOEntryID, aggrMOEntryMOID }
           ::= {aggrMOTable 1 }
       
       AggrMOEntry ::= SEQUENCE {
          aggrMOEntryID
                        Unsigned32,
          aggrMOEntryMOID
                        Unsigned32,
          aggrMOInstance
                        OBJECT IDENTIFIER,
          aggrMODescr
                        SnmpAdminString,
          aggrMOEntryStorageType
                        StorageType,
          aggrMOEntryStatus
                        RowStatus
       }

aggrMOEntryID OBJECT-TYPE

           SYNTAX Unsigned32 (1..2147483647)
           MAX-ACCESS not-accessible
           STATUS current
           DESCRIPTION
             "An index uniquely identifying a group of MOs
              that will be aggregated."
           ::= { aggrMOEntry 1 }

aggrMOEntryMOID OBJECT-TYPE

           SYNTAX Unsigned32 (1..65535)
           MAX-ACCESS not-accessible
           STATUS current
           DESCRIPTION
             "An index to uniquely identify an MO instance in the
              group of MO instances that will be aggregated."
           ::= { aggrMOEntry 2 }

aggrMOInstance OBJECT-TYPE

SYNTAX OBJECT IDENTIFIER
MAX-ACCESS read-create
STATUS current
DESCRIPTION

"The OID of the MO instance, the value of which will

be sampled by the agent."

           ::= { aggrMOEntry 3 }

aggrMODescr OBJECT-TYPE

           SYNTAX SnmpAdminString (SIZE(0..64))
           MAX-ACCESS read-create
           STATUS current
           DESCRIPTION
              "A textual description of the object that will
               be aggregated."
           ::= {aggrMOEntry 4}

aggrMOEntryStorageType OBJECT-TYPE

           SYNTAX StorageType
           MAX-ACCESS read-create
           STATUS current
           DESCRIPTION
              "This object defines whether the parameters defined in
               this row are kept in volatile storage and lost upon
               reboot or backed up by non-volatile (permanent)
               storage.
               Conceptual rows having the value 'permanent' need not
               allow write-access to any columnar objects in the row.
              "
           ::= {aggrMOEntry 5}

aggrMOEntryStatus OBJECT-TYPE

           SYNTAX RowStatus
           MAX-ACCESS read-create
           STATUS current
           DESCRIPTION
              "The row status variable, used according to row
               installation and removal conventions.
               Objects in a row can be modified only when the value of
               this object in the corresponding conceptual row is not
               'active'.
               Thus, to modify one or more of the objects in this
               conceptual row,
                 a. change the row status to 'notInService',
                 b. change the values of the row, and
                 c. change the row status to 'active'.
               The aggrMOEntryStatus may be changed to 'active' iff
               all the MOs in the conceptual row have been assigned
               valid values.
              "
           ::= {aggrMOEntry 6}
      
      --
      -- aggrDataTable: The Table of Data.  Each row represents a Data
      --                set.  aggrCtlEntryID is the key to the table.
      --                It is used to identify instances of the
      --                aggregated MO that are present in the table.
      --
      aggrDataTable OBJECT-TYPE
           SYNTAX  SEQUENCE OF AggrDataEntry
           MAX-ACCESS  not-accessible
           STATUS  current
           DESCRIPTION
              "Each row of this table contains information
               about an aggregateMO indexed by aggrCtlEntryID."
           ::= {aggrMIB 3}

aggrDataEntry OBJECT-TYPE

           SYNTAX  AggrDataEntry
           MAX-ACCESS  not-accessible
           STATUS  current
           DESCRIPTION
              "Entry containing information pertaining to
               an aggregate MO."
           INDEX {aggrCtlEntryID}
           ::= {aggrDataTable 1 }

AggrDataEntry ::= SEQUENCE {

         aggrDataRecord
                    AggrMOValue,
         aggrDataRecordCompressed
                    AggrMOCompressedValue,
         aggrDataErrorRecord
                    AggrMOErrorStatus
         }

aggrDataRecord OBJECT-TYPE

           SYNTAX AggrMOValue
           MAX-ACCESS read-only
           STATUS current
           DESCRIPTION
             "The snapshot value of the aggregated MO.
              Note that the access privileges to this object will be
              governed by the access privileges of the component
              objects.  Thus, an entity attempting to access an
              instance of this MO MUST have access rights to all the
              component instance objects and this MO instance.
             "
           ::= { aggrDataEntry 1}

aggrDataRecordCompressed OBJECT-TYPE

           SYNTAX AggrMOCompressedValue
           MAX-ACCESS read-only
           STATUS current
           DESCRIPTION
             "The compressed value of the aggregated MO.
              The compression algorithm will depend on the
              aggrCtlCompressionAlgorithm given in the corresponding
              aggrCtlEntry.  If the value of the corresponding
              aggrCtlCompressionAlgorithm is (1) 'none', then the value
              of all instances of this object will be a string of zero
              length.
              Note that the access privileges to this object will be
              governed by the access privileges of the component
              objects.  Thus, an entity attempting to access an instance
              of this MO MUST have access rights to all the component
              instance objects and this MO instance.
             "
           ::= { aggrDataEntry 2}

aggrDataErrorRecord OBJECT-TYPE

           SYNTAX AggrMOErrorStatus
           MAX-ACCESS read-only
           STATUS current
           DESCRIPTION
              "The error status corresponding to the MO instances
               aggregated in aggrDataRecord (and
               aggrDataRecordCompressed)."
           ::= { aggrDataEntry 3}
      
       -- Conformance information
      aggrConformance OBJECT IDENTIFIER ::= { aggrMIB 4 }
      aggrGroups      OBJECT IDENTIFIER ::= { aggrConformance 1 }
      aggrCompliances OBJECT IDENTIFIER ::= { aggrConformance 2 }
      
       -- Compliance statements
      aggrMibCompliance MODULE-COMPLIANCE
           STATUS  current
           DESCRIPTION
                   "The compliance statement for SNMP entities
                    that implement the AGGREGATE-MIB."
           MODULE  -- this module
               MANDATORY-GROUPS { aggrMibBasicGroup }
           ::= { aggrCompliances 1 }
      
       -- Units of conformance
      aggrMibBasicGroup    OBJECT-GROUP
           OBJECTS {
                      aggrCtlMOIndex,
                      aggrCtlMODescr,
                      aggrCtlCompressionAlgorithm,
                      aggrCtlEntryOwner,
                      aggrCtlEntryStorageType,
                      aggrCtlEntryStatus,
                      aggrMOInstance,
                      aggrMODescr,
                      aggrMOEntryStorageType,
                      aggrMOEntryStatus,
                      aggrDataRecord,
                      aggrDataRecordCompressed,
                      aggrDataErrorRecord
          }
           STATUS  current
           DESCRIPTION
                   "A collection of objects for aggregation of MOs."
           ::= { aggrGroups 1 }
      END
      
      TIME-AGGREGATE-MIB DEFINITIONS ::= BEGIN
       IMPORTS
         MODULE-IDENTITY,  experimental,
         OBJECT-TYPE,      Opaque, Integer32
                    FROM SNMPv2-SMI
         OwnerString
                    FROM RMON-MIB
         RowStatus, StorageType, TEXTUAL-CONVENTION
                    FROM SNMPv2-TC
         MODULE-COMPLIANCE, OBJECT-GROUP
                    FROM SNMPv2-CONF
         SnmpAdminString
                    FROM SNMP-FRAMEWORK-MIB;

tAggrMIB MODULE-IDENTITY

          LAST-UPDATED "200604270000Z"        --  27 April 2006
          ORGANIZATION "Cyber Solutions Inc. NetMan Working Group"
          CONTACT-INFO
         "                      Glenn Mansfield Keeni
                        Postal: Cyber Solutions Inc.
                                6-6-3, Minami Yoshinari
                                Aoba-ku, Sendai, Japan 989-3204.
                           Tel: +81-22-303-4012
                           Fax: +81-22-303-4015
                        E-mail: glenn@cysols.com

Support Group E-mail: mibsupport@cysols.com"

             DESCRIPTION

"The MIB for servicing Time-Based aggregate

objects.

                       Copyright © The Internet Society (2006).  This
                       version of this MIB module is part of RFC 4498;
                       see the RFC itself for full legal notices.
                     "
             REVISION    "200604270000Z"      -- 27th April, 2006
             DESCRIPTION "Initial version, published as RFC 4498."
                  ::= { experimental 124 }

TAggrMOErrorStatus ::= TEXTUAL-CONVENTION

        STATUS       current
        DESCRIPTION
          "This data type is used to model the error status of the
           sampled MO instance.  The error status for a sampled MO
           instance is given in terms of two elements:
             o The moIndex, which indicates the sample number of the MO
               instance (starting at 1) in the value of the time-
               aggregated MO instance.
             o The moError, which indicates the error that was
               encountered in sampling that MO instance.
           The syntax in ASN.1 Notation will be
           ErrorStatus :: = SEQUENCE {
              moIndex  Integer32,
              moError  SnmpPduErrorStatus
           }
           TAggrMOErrorStatus ::= SEQUENCE OF {
              ErrorStatus
           }
           Note1: The command responder will supply values for all
                  the samples of the MO instance.  If an error is
                  encountered for a sample, then the corresponding
                  value will have an ASN.1 value NULL, and an error
                  will be flagged in the corresponding
                  TAggrMOErrorStatus object.
                  Only MOs for which errors have been encountered will
                  the corresponding moIndex and moError values be set.
           Note2: The error code for the component MO instances will be
                  in accordance with the SnmpPduErrorStatus TC defined
                  in the DISMAN-SCHEDULE-MIB[RFC3231].
          "
        SYNTAX      Opaque (SIZE (0..1024))

TimeAggrMOValue ::= TEXTUAL-CONVENTION

        STATUS       current
        DESCRIPTION
          "This data type is used to model the time-aggregated MOs.  It
        
           will be a sequence of values.  The syntax in ASN.1 Notation
           will be
           MOSampleValue :: = SEQUENCE {
                value ObjectSyntax
           }
           TimeAggrMOValue ::= SEQUENCE OF {
                MOSampleValue
           }
           where the first MOSampleValue, if any, will always be the
           timestamp of the first sample in the aggregated object.  The
           subsequent values are the values of the MO instance sampled
           at the specified intervals for the specified number of times.
           Note: The command generator will need to know the
                 constituent MO instance and the sampling interval to
                 correctly interpret TimeAggrMOValue.
          "
        SYNTAX      Opaque (SIZE (0..1024))

CompressedTimeAggrMOValue ::= TEXTUAL-CONVENTION

        STATUS       current
        DESCRIPTION
          "This data type is used to model the compressed
           TAgMOs."
        SYNTAX      Opaque (SIZE (0..1024))
   
   --
   -- The Time-Based aggregation control table
   --
      tAggrCtlTable OBJECT-TYPE
           SYNTAX  SEQUENCE OF TAggrCtlEntry
           MAX-ACCESS  not-accessible
           STATUS current
           DESCRIPTION
              "The Time-Based aggregation control table.  It controls
               the aggregation of the samples of MO instances.  There
               will be a row for each TAgMO.
              "
           ::= {tAggrMIB 1}

tAggrCtlEntry OBJECT-TYPE

           SYNTAX  TAggrCtlEntry
           MAX-ACCESS  not-accessible
           STATUS  current
           DESCRIPTION
             "A row of the control table that defines one Time-Based
              aggregate MO (TAgMO)."
           INDEX {tAggrCtlEntryID }
           ::= {tAggrCtlTable 1 }
       TAggrCtlEntry ::= SEQUENCE {
          tAggrCtlEntryID
                        SnmpAdminString,
          tAggrCtlMOInstance
                        OBJECT IDENTIFIER,
          tAggrCtlAgMODescr
                        SnmpAdminString,
          tAggrCtlInterval
                        Integer32,
          tAggrCtlSamples
                        Integer32,
          tAggrCtlCompressionAlgorithm
                        INTEGER,
          tAggrCtlEntryOwner
                        OwnerString,
          tAggrCtlEntryStorageType
                        StorageType,
          tAggrCtlEntryStatus
                        RowStatus
       }

tAggrCtlEntryID OBJECT-TYPE

           SYNTAX SnmpAdminString (SIZE(1..32))
           MAX-ACCESS not-accessible
           STATUS current
           DESCRIPTION
             "A locally unique, administratively assigned name
               for this aggregated MO.  It is used as an index to
               uniquely identify this row in the table."
           ::= { tAggrCtlEntry 1 }

tAggrCtlMOInstance OBJECT-TYPE

           SYNTAX OBJECT IDENTIFIER
           MAX-ACCESS read-create
           STATUS current
           DESCRIPTION
              "The sampled values of this MO instance will be
               aggregated by the TAgMO.
               "
           ::= { tAggrCtlEntry 2 }

tAggrCtlAgMODescr OBJECT-TYPE

           SYNTAX SnmpAdminString (SIZE(0..64))
           MAX-ACCESS read-create
           STATUS current
           DESCRIPTION
              "A textual description of the aggregate object."
           ::= {tAggrCtlEntry 3}

tAggrCtlInterval OBJECT-TYPE

           SYNTAX Integer32
           UNITS  "micro seconds"
           MAX-ACCESS read-create
           STATUS current
           DESCRIPTION
              "The interval, in microseconds, at which the MO instance
               pointed at by tAggrInstance will be sampled for
               Time-Based aggregation.
             "
           ::= {tAggrCtlEntry 4}

tAggrCtlSamples OBJECT-TYPE

           SYNTAX Integer32
           MAX-ACCESS read-create
           STATUS current
           DESCRIPTION
              "The number of times at which the MO instance referred
               to by tAggrInstance will be sampled for Time-Based
               aggregation."
           ::= {tAggrCtlEntry 5}

-- only one compression algorithm is defined as of now. tAggrCtlCompressionAlgorithm OBJECT-TYPE

           SYNTAX INTEGER {
                  none      (1),
                  deflate   (2)
           }
           MAX-ACCESS read-create
           STATUS current
           DESCRIPTION
              "The compression algorithm that will be used by
               the agent to compress the value of the TAgMO.
               The deflate algorithm and corresponding data format
               specification is described in RFC 1951.  It is
               compatible with the widely used gzip utility.
             "
           REFERENCE
             "RFC1951 : DEFLATE Compressed Data Format Specification
              version 1.3
             "
           DEFVAL { none }
           ::= {tAggrCtlEntry 6}

tAggrCtlEntryOwner OBJECT-TYPE

SYNTAX OwnerString
MAX-ACCESS read-create
STATUS current

           DESCRIPTION
              "A textual description of the entity that created
               this entry.
             "
           ::= {tAggrCtlEntry 7}

tAggrCtlEntryStorageType OBJECT-TYPE

           SYNTAX StorageType
           MAX-ACCESS read-create
           STATUS current
           DESCRIPTION
              "This object defines whether the parameters defined in
               this row are kept in volatile storage and lost upon
               reboot or backed up by non-volatile (permanent)
               storage.
               Conceptual rows having the value 'permanent' need not
               allow write-access to any columnar objects in the row.
              "
           ::= {tAggrCtlEntry 8}

tAggrCtlEntryStatus OBJECT-TYPE

           SYNTAX RowStatus
           MAX-ACCESS read-create
           STATUS current
           DESCRIPTION
              "The row status variable, used according to row
               installation and removal conventions.
               Objects in a row can be modified only when the value of
               this object in the corresponding conceptual row is not
               'active'.
               Thus, to modify one or more of the objects in this
               conceptual row,
                 a. change the row status to 'notInService',
                 b. change the values of the row, and
                 c. change the row status to 'active'.
               The tAggrCtlEntryStatus may be changed to 'active' iff
               all the MOs in the conceptual row have been assigned
               valid values.
              "
           ::= {tAggrCtlEntry 9}
      
      --
      -- tAggrDataTable: The data table.
      --
      tAggrDataTable OBJECT-TYPE
           SYNTAX  SEQUENCE OF TAggrDataEntry
           MAX-ACCESS  not-accessible
           STATUS  current
           DESCRIPTION
              "This is the data table.  Each row of this table contains
               information about a TAgMO indexed by tAggrCtlEntryID.
               tAggrCtlEntryID is the key to the table.  It is used to
               identify instances of the TAgMO that are present in the
               table.
             "
           ::= {tAggrMIB 2}

tAggrDataEntry OBJECT-TYPE

           SYNTAX  TAggrDataEntry
           MAX-ACCESS  not-accessible
           STATUS  current
           DESCRIPTION
             "Entry containing information pertaining
               to a TAgMO."
           INDEX {tAggrCtlEntryID}
           ::= {tAggrDataTable 1 }

TAggrDataEntry ::= SEQUENCE {

         tAggrDataRecord
                    TimeAggrMOValue,
         tAggrDataRecordCompressed
                    CompressedTimeAggrMOValue,
         tAggrDataErrorRecord
                    TAggrMOErrorStatus
         }

tAggrDataRecord OBJECT-TYPE

           SYNTAX TimeAggrMOValue
           MAX-ACCESS read-only
           STATUS current
           DESCRIPTION
             "The snapshot value of the TAgMO."
           ::= { tAggrDataEntry 1}

tAggrDataRecordCompressed OBJECT-TYPE

SYNTAX CompressedTimeAggrMOValue
MAX-ACCESS read-only
STATUS current
DESCRIPTION

"The compressed value of the TAgMO.

The compression algorithm will depend on the tAggrCtlCompressionAlgorithm given in the corresponding tAggrCtlEntry. If the value of the corresponding tAggrCtlCompressionAlgorithm is (1) 'none', then the

              value of all instances of this object will be a string
              of zero length.
              Note that the access privileges to this object will be
              governed by the access privileges of the corresponding MO
              instance.  Thus, an entity attempting to access an
              instance of this MO MUST have access rights to the
              instance object pointed at by tAggrCtlMOInstance and this
              MO instance.
             "
           ::= { tAggrDataEntry 2}

tAggrDataErrorRecord OBJECT-TYPE

           SYNTAX TAggrMOErrorStatus
           MAX-ACCESS read-only
           STATUS current
           DESCRIPTION
              "The error status corresponding to the MO instance
               samples aggregated in tAggrDataRecord (and
               tAggrDataRecordCompressed)."
           ::= { tAggrDataEntry 3}
      
       -- Conformance information
      tAggrConformance OBJECT IDENTIFIER ::= { tAggrMIB 3 }
      tAggrGroups      OBJECT IDENTIFIER ::= { tAggrConformance 1 }
      tAggrCompliances OBJECT IDENTIFIER ::= { tAggrConformance 2 }
      
       -- Compliance statements
      tAggrMibCompliance MODULE-COMPLIANCE
           STATUS  current
           DESCRIPTION
                   "The compliance statement for SNMP entities
                    that implement the TIME-AGGREGATE-MIB."
           MODULE  -- this module
               MANDATORY-GROUPS { tAggrMibBasicGroup }
           ::= { tAggrCompliances 1 }
      
       -- Units of conformance
      tAggrMibBasicGroup    OBJECT-GROUP
           OBJECTS {
                      tAggrCtlMOInstance,
                      tAggrCtlAgMODescr,
                      tAggrCtlInterval,
                      tAggrCtlSamples,
                      tAggrCtlCompressionAlgorithm,
                      tAggrCtlEntryOwner,
                      tAggrCtlEntryStorageType,
                      tAggrCtlEntryStatus,
                      tAggrDataRecord,
                      tAggrDataRecordCompressed,
                      tAggrDataErrorRecord
          }
           STATUS  current
           DESCRIPTION
                    "A collection of objects for Time-Based aggregation
                     of MOs."
           ::= { tAggrGroups 1 }
      END

7. Security Considerations

There are management objects in the MIB modules defined in this document that have a MAX-ACCESS clause of read-create. Such objects may be considered sensitive or vulnerable in some network environments. The support for SET operations in a non-secure environment without proper protection can have a negative effect on network operations. The objects and corresponding vulnerabilities are discussed below.

The following MOs are used to configure an agent that implements the aggregate MIB modules.

         aggrCtlMOIndex,
         aggrCtlMODescr,
         aggrCtlCompressionAlgorithm,
         aggrCtlEntryOwner,
         aggrCtlEntryStorageType,
         aggrCtlEntryStatus,
         aggrMOInstance,
         aggrMODescr,
         aggrMOEntryStorageType,
         aggrMOEntryStatus,
         tAggrCtlMOInstance,
         tAggrCtlAgMODescr,
         tAggrCtlInterval,
         tAggrCtlSamples,
         tAggrCtlCompressionAlgorithm,
         tAggrCtlEntryOwner,
         tAggrCtlEntryStorageType,
         tAggrCtlEntryStatus,

Access to these objects may be abused to affect the operation of the data collection system. In particular,

  • by changing the value of an instance of aggrCtlEntryStatus, tAggrCtlEntryStatus, aggrMOEntryStatus, or tAggrMOEntryStatus to 'notInService' or 'destroy', the data aggregation operation for the corresponding entry will become unavailable to the management system.
  • by changing the value of an instance of aggrMOInstance or tAggrCtlMOInstance, the data aggregation operation may be subverted. This may result in wrong information being fed to the management system.
  • by adding several rows in the aggrMOTable corresponding to an aggregate MO, it is possible to make the value of the aggregate MOs very large. A similar effect may be achieved by manipulating the value of the tAggrCtlSamples instance corresponding to a Time-Based aggregate MO. This could result in very heavy management traffic and/or fragmentation of response packets. In some cases the responder may refuse to send the data and will simply respond with an error message indicating that the response packet size is too big.

An entity attempting to access an instance of an aggregated MO MUST have access rights to all the component instance objects and the aggregate MO instance. An implementation MUST follow this requirement. Lax adherence to this requirement will breach the security model and make the system vulnerable to illegal accesses.

SNMP versions prior to SNMPv3 did not include adequate security. Even if the network itself is secure (for example by using IPSec), there is no control as to who on the secure network is allowed to access and GET/SET (read/change/create/delete) the objects in this MIB module.

It is RECOMMENDED that implementers consider the security features as provided by the SNMPv3 framework (see [RFC3410], section 8), including full support for the SNMPv3 cryptographic mechanisms (for authentication and privacy).

Further, deployment of SNMP versions prior to SNMPv3 is NOT RECOMMENDED. Instead, it is RECOMMENDED to deploy SNMPv3 and to enable cryptographic security. It is then a customer/operator responsibility to ensure that the SNMP entity giving access to an instance of this MIB module is properly configured to give access to the objects only to those principals (users) that have legitimate rights to indeed GET or SET (change/create/delete) them.

8. IANA Considerations

The MIB modules in this document use the following IANA-assigned OBJECT IDENTIFIER values, recorded in the SMI Numbers registry:

   Descriptor        OBJECT IDENTIFIER value
   ----------        -----------------------
   aggrMIB           { experimental 123 }
   tAggrMIB          { experimental 124 }

9. References

9.1. Normative References

   [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
             Requirement Levels", BCP 14, RFC 2119, March 1997.
   
   [RFC2578] McCloghrie, K., Perkins, D., and J. Schoenwaelder,
             "Structure of Management Information Version 2 (SMIv2)",
             STD 58, RFC 2578, April 1999.
   
   [RFC2579] McCloghrie, K., Perkins, D., and J. Schoenwaelder, "Textual
             Conventions for SMIv2", STD 58, RFC 2579, April 1999.
   
   [RFC2580] McCloghrie, K., Perkins, D., and J. Schoenwaelder,
             "Conformance Statements for SMIv2", STD 58, RFC 2580, April
             1999.
   
   [RFC2819] Waldbusser, S., "Remote Network Monitoring Management
             Information Base", STD 59, RFC 2819, May 2000.
   
   [RFC3411] Harrington, D., Presuhn, R., and B. Wijnen, "An
             Architecture for Describing Simple Network Management
             Protocol (SNMP) Management Frameworks", STD 62, RFC 3411,
             December 2002.
   
   [RFC3231] Levi, D. and J. Schoenwaelder, "Definitions of Managed
             Objects for Scheduling Management Operations", RFC 3231,
             January 2002.
   
   [RFC1951] Deutsch, P., "DEFLATE Compressed Data Format Specification
             version 1.3", RFC 1951, May 1996.

9.2. Informative References

   [RFC3410] Case, J., Mundy, R., Partain, D., and B. Stewart,
             "Introduction and Applicability Statements for Internet-
             Standard Management Framework", RFC 3410, December 2002.

10. Acknowledgements

This document is the product of discussions and deliberations carried out in the WIDE-netman group. Bert Wijnen and Glenn Waters reviewed the document and provided valuable comments.

Authors' Addresses

   Glenn Mansfield Keeni
   Cyber Solutions Inc.
   6-6-3 Minami Yoshinari
   Aoba-ku, Sendai 989-3204
   Japan
   
   Phone: +81-22-303-4012
   EMail: glenn@cysols.com

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